ABSTRACT
The linear complex effect, nonlinear secondary complex effect, the dispersion effect, interfacial effect, and so on, of fiber-reinforced composite materials are examined depending on modification of the reinforcing fibers and interface, and on the type of sizing agent and matrix resin used. Recently, interfaces between fibers and resins have been investigated from the viewpoint of a thickness rather than as a plane generally having no thickness. However, most of the “contents of interfaces” and bonding mechanisms have not been elucidated, because interfaces are ready to be stained and have extremely small thicknesses, if any. The roles or functions of the interfaces are different depending not only on the surface characteristics of the constituent materials but also on the characteristics of the materials in the bulk state. It is very difficult to describe generally the roles of interfaces. In this chapter we discuss the interfacial effect and the roles that interfaces or interlayers of carbon-fiber-reinforced composite materials play in the strength of unidirectionally reinforced materails and laminates.
